The proposed studies involve continued investigations of the quaternary structures of large biological molecules, partcularly enzymes and nucleic acids. Major emphasis will be directed to further elucidation of the quaternary structures of biotic-containing enzymes. Pyruvate carboxylase from Pseudomonas citronellolis, appears to have an a4 b4 structure with a tetrahedral conformation in contrast to animal and yeast varieties of the enzyme which are of similar molecular weight but with an a4 structure with rhombiod conformations. These tentative conclusions will be tested by further studies using specific antibodies against the biotin site and against specific polypeptides. Monoclonal antibodies are also being developed. Another project involves the biotin-containing enzyme, transcarboxylase. This very large enzyme consists of a core structure surrounded by as many as six peripheral subunits attached to the core by biotin-containing polypeptides. Better definition of the core structure will be sought by EM studies involving microcrystals. In addition, the quaternary structures of enzymes for different species of Propionibacterium will be examined by EM procedures. Co2 plus appears to stabilize the enzyme. The effect of the metal of quaternary structures as visualized by EM will be carried out.